This proposal seeks funds for a Boston site to develop, demonstrate and evaluate the effectiveness of a comprehensive community outreach model to prevent the spread of HIV among IVDU's who are not in treatment. The proposed model for Boston seeks to send outreach workers to all major segments of the IVDU population, develop more highly effective behavior-change interventions, coordinate all existing AIDS-related resources and services for IVDU's, and conduct an epidemilogical survey of antibody status to target the outreach more effectively and motivate community change. The outreach will be to street IVDU's, sex-partners, middle class IVDU's, IVDU prostitutes, recovering IVDU'S, IVDU'S in the medical care and criminal justice systems and IVDU'S who are seeking antibody testing from a site specially established for them as part of this project. On the basis of prior research, the P.I. believes that a great need at this time is to intensify the behavior-change component of the outreach model. The local evaluation design will therefore randomly assign 16 areas of Boston (stratified by ethnicity and matched on the rate of HIV infection) to either the standard behavior change intervention or an enhanced intervention that adds wither intensive follow-up counseling or a permanent AIDS- prevention community organizer to the standard outreach package. Estimates of the effectiveness of the interventions will stem from baseline and followup interviews and antibody testing with a cohort of 1000 IVDU's (65 from each area) who were antibody negative before the intervention. There will also be a local process evaluation based primarily on ethnographic observation, interviews and utilization of services. The outreach workers will also conduct baseline and followup interviews as part of a national outcome evaluation. Prior experience in a very similar study in Baltimore has allowed the study team to design the intervention levels, avoid evaluation design pitfalls and anticipate problems of outreach implementation.